Researchers are concerned that the weight of the average American school child is increasing implying, among other things, that children’s clothing should be manufactured and marketed in larger sizes. If X is the weight of school children sampled in a nationwide study and Y is their grade level in school, then

a) Both X and Y are examples of categorical variables.
b) Both X and Y are examples of quantitative variables.
c) X is an example of a quantitative variable and Y is an example of a categorical variable.
d) X is an example of a categorical variable and Y is an example of a quantitative variable